A fractal-based printed slot antenna for multi-band wireless applications

Fractal geometries have shown to be attractive for antenna designers because of the unique features they ofier. In this paper, a printed fractal based slot antenna has been introduced to be used in multi-band wireless applications. The slot structure of the proposed antenna is of an octagonal shape with a Koch fractal curve of the second iteration is applied on each of its sides. The slot structure has been etched on the ground plane of a substrate with relative permittivity of 4.4 and 1.6mm thickness. On the reverse side of the substrate, a 50ohm microstrip line feed has been etched. To enhance the coupling with the slot, the feed line has been loaded with a circular stub with embedded complementary circular split ring resonator. Based on the lowest resonant frequency, it has been found that the largest dimension of the proposed antenna slot structure is less than half the guided wavelength. Parametric study shows that the resulting antenna ofiers a multi-band behavior with enhanced gain and fractional bandwidths, besides the reasonable radiation characteristics throughout the resonating bands. With appropriate dimension scaling, the proposed antenna could be a suitable candidate for use in a wide variety of multi functions wireless applications.